Since 1997 when the wireless local area network standard Institute of Electrical and Electronics Engineers (IEEE) 802.11 was released, and under a vigorous promotion by the Wireless Fidelity (WiFi) Alliance formed by numerous leading companies in the industry, the WiFi technology has been developing rapidly due to its advantages, such as rapid deployment, convenient use, and a high transmission rate. Because mobile terminal devices nowadays, such as a notebook computer, a personal digital assistant (PDA), and a cell phone, all support the WiFi technology and users have a requirement of mobile working, the WiFi technology is widely applied to various industries. WiFi network access points are distributed throughout locations such as a hotel, a cafe, a school, and a hospital. It may be said that, WiFi is everywhere in life.
Generally speaking, a characteristic of a WiFi network is that one Access Point (AP) provides an access service for a plurality of stations (STAs). The AP and STAs perform information interaction using a wireless signal. From a perspective of a Media Access Control (MAC) layer, a unit of the information interaction between the AP and the STAs is a frame. That is, the AP sends one or more frames to the STAs, and alternately, the STAs also send one or more frames to the AP. These frames have a specific structure: a former part of a frame is a frame header, which may also be referred to as a MAC header; and a latter part of a frame is used for carrying a data section. For each type of frame, a structure of the MAC header is relatively fixed, and a length is also relatively fixed. However, a length of the data section varies with an actual situation.
For a transmission requirement, the MAC header carries a destination address and a source address. The destination address is used to represent to whom this frame is sent, that is, a frame receiver; and the source address is used to represent from whom this frame is sent, that is, a frame transmitter. In the existing wireless local area network standard IEEE 802.11, the destination address and the source address are a MAC address of a target device and a MAC address of a source device respectively, and they both have 48 bits. In the existing IEEE 802.11 standard, the MAC frame header may actually involve a maximum of four addresses, which respectively represent a source address, an address of a current transmitter, an address of a current receiver, and an ultimate target address. The source address mentioned in the specification refers to the current transmitter address in the standard, which may be the same as the source address. The destination address mentioned in the specification refers to the current receiver address in the standard, which may be the same as the ultimate target address.
An AP of a WiFi broadcasts a beacon (beacon frame) frame periodically. The beacon frame carries various network information of the AP, for example, information such as a name of the network, a MAC address of the AP, and a period of the beacon frame. An STA may learn the network information by monitoring the beacon frame.
In addition, the WiFi standard IEEE 802.11ah mainly applies to fields of a smart grid, a sensor network, and the like. Data transmission of the WiFi standard IEEE 802.11ah is characterized in a low transmission rate and a small amount of data transmitted each time. Because a MAC header is carried in transmitted data during each transmission process, if the amount of the transmitted data is not large, a proportion occupied by the MAC header is obvious. Therefore, compression of the MAC header is considered. A specific implementation method is to compress an original 48-bit MAC address into a 16-bit STA identification number or an auxiliary identifier (AID) and/or an AP identification number or an auxiliary identifier (APID). These shorter identification numbers may be referred to as auxiliary identifiers and be used as addresses shorter than the MAC. In this way, a downlink destination address may be indicated using an AID, and a source address may be indicated using an APID; and an uplink destination address may be indicated using an APID, and a source address may be indicated using an AID. Generally speaking, an AID is an STA identification number allocated by an AP and has 16 bits; and an APID is an identification number generated using a certain method to identify an AP and also has 16 bits. The method for generating an APID, for example, may be to obtain a 16-bit identification number from a 48-bit MAC address of an AP after hash calculation. Therefore, it may be seen that, after compression of a MAC header, when an AP communicates with an STA, addresses of the AP and STA are no longer identified using the respective MAC addresses but are identified using an APID and an AID respectively.
Generally speaking, for a beacon frame, an association response frame, a re-association response frame, or an auxiliary identifier update frame sent by an AP, a frame header includes a MAC address of the AP, and a frame body includes an APID of the AP. However, for other data frames or management frames, in a transmission manner using MAC header compression, source addresses and destination addresses in frame headers of these data frames or management frames are all identified by AID/APID.
However, there is a possibility of an address conflict in an actual application of identification using an APID and an AID after MAC header compression. For example, APIDs of two adjacent APs may be the same (for example, when 100 APs coexist, a possibility of occurrence of same APIDs is 7%). Uplink data sent to one of the APs by an STA may be received by the other AP, and the other AP mistakenly assumes that the uplink data is sent to the other AP itself; or an STA is waiting to receive downlink data from one of the APs, but receives downlink data sent by the other AP and therefore mistakenly assumes that the downlink data is sent to the STA itself. This may cause unnecessary trouble. For example, after receiving data and performing some decoding operations, the AP or STA finds that the data is not sent to the AP or STA itself, and then needs to discard the received data, thereby exercising in futility.